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ChEBI: A pyranone that is 4H-pyran substituted by an oxo group at position 4.

1) from Diethylacetone dioxalate by cyclization to Chelidonic acid (gamma-Pyrone- 2,6-dicarboxylic acid). The acid yields 4H-Pyran-4-one by decarboxylation.
2) by heating of I-Methoxypent-l -en-3-yn-5- al diethylacetal with Methanol and water, using Mercuric sulfate or Sulfuric acid catalyst.

Purify -pyrone by vacuum distillation; the distillate crystallises and is hygroscopic. It is non-steam vola